I don't have WHS so can't confirm if any of these work on that, but below are some services that I have used successfully on 2000 and XP. I've listed geographical location, as I've found it can have a significant impact on speed:
- SpiderOak (US west coast) - needs their software and is both a sync and backup tool
- Dropbox (US and Europe) - needs their software, and is really meant as a sync tool, less flexible than SpiderOak
- Humyo (UK) - uses their software or WebDAV over SSL
- MyDisk (Sweden) - WebDAV with a Java-based backup client, or web folders.
Sorry for not linking, but I'm under the novice links limitation. The WebDAV ones will work as a mapped drive using Netdrive. All the above have a web interface to let you recovery individual files. Dropbox and SpiderOak have file version history.
Another possibility is Crashplan. Their software is now free, which could let you partner with someone else, so that you back up to them and they back up to you. All encrypted of course, but it does mean opening a port on your firewall.